Precise beam-tilt alignment and collimation are required to minimize the phase error associated with coma in high-resolution cryo-EM.

ABSTRACT: Electron microscopy at a resolution of 0.4nm or better requires more careful adjustment of the illumination than is the case at a resolution of 0.8nm. The use of current-axis alignment is not always sufficient, for example, to avoid the introduction of large phase errors, at higher resolution, due to axial coma. In addition, one must also ensure that off-axis coma does not corrupt the data quality at the higher resolution. We particularly emphasize that the standard CTF correction does not account for the phase error associated with coma. We explain the cause of both axial coma and the typically most troublesome component of off-axis coma in terms of the well-known shift of the electron diffraction pattern relative to the optical axis that occurs when the illumination is not parallel to th

SUBMITTER: Glaeser RM 

PROVIDER: S-EPMC3056894 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature